From Homestar Runner Wiki

When The Brothers Chaps don't have anything ready to release on Monday morning (or very rarely on other days), they frequently let viewers know via a Main Page message that there will be an email or other new toon soon so that viewers will know to check back before the next week. When they say "soon", they almost always mean either later in the same day or sometime the next day (except for the two most recent big Halloween toons, which each had teasers and took several days to be released).